While nitrogen is of primary importance in the renovation of sewage, excessive concentrations of nitrogen compounds in groundwater are a public health hazard and also contribute to the eutrophication of surface water. The presence of nitrite (NO.sub.2 --) and, indirectly, nitrate (NO.sub.3 --), in drinking water may lead to methemoglobinemia which can impair oxygen transport in the blood, particularly in infants where gastrointestinal upsets can encourage reduction of nitrite to nitrate. The hazards of these materials and their precursors, the nitrosamines, in the soil and acquifer are explained in detail in the New Jersey Pinelands, Comprehensive Management Plan, New Jersey Pinelands Protection Act, 1979, adopted Nov. 21, 1980, pages 51-53, which is incorporated herein by reference. Many other states and the federal government have adopted standards for limiting the amounts of nitrates which may be released to the acquifer.